Scattering forces from the curl of the spin angular momentum of a light field

Light forces on small (Rayleigh) particles are usually described as the sum of two terms: the dipolar or gradient force and the scattering or radiation pressure force. The scattering force is traditionally considered proportional to the Poynting vector, which gives the direction and magnitude of the momentum flow. However, as we will show, there is an additional nonconservative contribution to the scattering force arising in a light field with nonuniform helicity. This force is shown to be proportional to the curl of the spin angular momentum of the light field. The relevance of the spin force is illustrated in the simple case of a 2D field geometry arising in the intersection region of two standing wavesThis work was supported by the Spanish MEC through the Consolider NanoLight (CSD2007-00046), FIS2005-05137 and FIS2006-11170-C02-02 projects, Microseres-CM and by the Spanish-French PICASSO program (HF2007- 0068

Radiative heat transfer from a black body to dielectric nanoparticles

International audienceHeating of dielectric nanoparticles by black-body radiation is investigated by using molecular-dynamics simulation. The thermal interaction with the radiation is modeled by coupling the ions with a random electric field and including a radiation reaction force. This approach shows that the heat is absorbed by the polariton mode. Its subsequent redistribution among other vibration modes strongly depends on the particle size and on temperature.We observe energy trapping in a finite subset of vibrational mode

Quantum thermal bath for molecular dynamics simulation

International audienceMolecular dynamics (MD) is a numerical simulation technique based on classical mechanics. It has been taken for granted that its use is limited to a large temperature regime where classical statistics is valid. To overcome this limitation, the authors introduce in a universal way a quantum thermal bath that accounts for quantum statistics while using standard MD. The efficiency of the new technique is illustrated by reproducing several experimental data at low temperatures in a regime where quantum statistical effects cannot be neglected

Optical extinction in a single layer of nanorods

We demonstrate that almost 100 % of incident photons can interact with a monolayer of scatterers in a symmetrical environment. Nearly-perfect optical extinction through free-standing transparent nanorod arrays has been measured. The sharp spectral opacity window, in the form of a characteristic Fano resonance, arises from the coherent multiple scattering in the array. In addition, we show that nanorods made of absorbing material exhibit a 25-fold absorption enhancement per unit volume compared to unstructured thin film. These results open new perspectives for light management in high-Q, low volume dielectric nanostructures, with potential applications in optical systems, spectroscopy, and optomechanics

Oxide phosphors for light upconversion; Yb3+ and Tm3+ co-doped Y2BaZnO5

Copyright 2011 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 109, 063104 (2011) and may be found at

Near-field induction heating of metallic nanoparticles due to infrared magnetic dipole contribution

We revisit the electromagnetic heat transfer between a metallic nanoparticle and a metallic semi-infinite substrate, commonly studied using the electric dipole approximation. For infrared and microwave frequencies, we find that the magnetic polarizability of the particle is larger than the electric one. We also find that the local density of states in the near field is dominated by the magnetic contribution. As a consequence, the power absorbed by the particle in the near field is due to dissipation by fluctuating eddy currents. These results show that a number of near-field effects involving metallic particles should be affected by the fluctuating magnetic fields.Comment: publi\'e dans Physical Review B 77 (2008), version avant revie

Rôle des ondes de surface dans la modification des propriétés radiatives de matériaux microstructurés. Application à la conception de sources infrarouges et à l'effet thermophotovoltaïque.

The existence of surface waves on materials like metals, doped semiconductors, polar materials or photonic crystals modifies their radiative properties.The 1st part of this thesis deals with the coherent and amplified thermal emission by surface plasmon-polaritons. We have designed and fabricated a highly directional tungsten thermal source in the near infrared. We have also studied the radiative cooling of doped silicon thanks to the amplified thermal emission by surface plasmons. We have compared the efficiencies of those coherent sources with the one of an anti-reflective system : the Salisbury screen.In the 2nd part, we study the impact of the near-field radiative transfer on thermophotovoltaic (TPV) energy conversion. The resonant excitation of surface waves on the thermal source illuminating the TPV cell generates an amplified and quasi-monochromatic radiative transfer. We propose a quantitative model of the calculation of the photogeneration current and the efficiency. We show a significant enhancement of both the efficiency and the output electric power of a near-field TPV converter.The 3rd part is dedicated to the radiative properties of photonic crystals induced by surface waves. Two phenomena known in plasmonics have been obtained : the resonant transmission through an opaque film and the coherent thermal emission. A key advantage of photonic crystals is that the resonant frequency can be modified by changing the lattice parameters.La présence d'ondes de surface sur certains matériaux (métaux, semiconducteurs dopés, cristaux polaires, cristaux photoniques) modifie leurs propriétés radiatives.La 1ère partie de cette thèse est consacrée au phénomène d'émission thermique cohérente et amplifiée par plasmon-polaritons de surface. Nous avons tout d'abord conçu et réalisé une source thermique de tungstène avec une directivité exceptionnelle dans le proche infrarouge. Nous avons ensuite étudié le refroidissement radiatif du silicium dopé grâce à l'amplification d'émission thermique par plasmons de surface. Nous avons comparé les performances de ces sources cohérentes avec celles d'un système anti-réfléchissant : l'écran de Salisbury.Dans la 2ème partie, nous étudions l'impact du transfert radiatif en champ proche sur la conversion thermophotovoltaïque (TPV). L'excitation d'ondes de surface sur la source éclairant la cellule TPV engendre un transfert radiatif amplifié et quasi-monochromatique. Nous présentons un modèle quantitatif permettant de calculer le photocourant et le rendement. Nous montrons que l'on peut obtenir une augmentation significative de la puissance électrique extraite et du rendement d'un dispositif TPV éclairé en champ proche.La 3ème partie porte sur les propriétés radiatives des cristaux photoniques induites par ondes de surface. Deux phénomènes connus en plasmonique ont pu être obtenus : la transmission résonante à travers un film opaque et l'émission thermique cohérente. Un avantage des cristaux photoniques est la possibilité de modifier la fréquence d'excitation des ondes de surface en faisant varier les paramètres du cristal